Few warriors enter battle without the protection of armour. To represent this, your opponent can make an 'Armour Save' roll for each wound caused by your shooting. To make an Armour Save roll, roll a D6 for the wounded model and compare the result to that model's armour value:
If the Armour Save roll equals or exceeds the model's armour value, the model is saved by its armour and the wound discarded.
If the result is less than the model's armour value, the model's armour has proved ineffective and the wound is 'unsaved'.
Rolls of a Natural 1
Even the heaviest and most finely crafted of armour has gaps in it. When making an Armour Save roll (of any type), a roll of a natural 1 is always a fail, regardless of modifiers.